Knight/Monk?
d12 hit die, 4+Int skills/leve, max BAB, max saves.
Maybe not the greatest synergy, since knights love armor and shields, but a lot of versatility.
And hell, if you make it to high levels, some crazy abilities:
1) Bonus Feat (Monk), Flurry of Blows, Unarmed Strike, FIghting Challenge +1, Knight's Challenge, Knight's Code
2) Bonus Feat (Monk), Evasion, Mounted Combat, Shield Block +1
3) Still Mind, Bulwark of Defense
4) Ki Strike (Magic), Slow Fall 20, Armor Mastery (Medium), Test of Mettle
5) Purity of Body, Bonus Feat (Knight), Vigilant Defender
6) Bonus Feat (Monk), Slow Fall 30, Shield Ally
7) Wholeness of Body, Fighting Challenge +2
8) Slow Fall 40, Call to Battle
9) Improved Evasion, Armor Mastery (Heavy)
10) Ki Strike (Lawful), Slow Fall 50, Bonus Feat (Knight)
11) Diamond Body, Greater Flurry, Shield Block +2
12) Abundant Step, Slow Fall 60, Daunting Challenge
13) Diamond Soul, Fighting Challenge +3
14) Slow Fall 70, Improved Shield Ally
15) Quivering Palm, Bonus Feat (Knight)
16) Ki Strike (Adamantine), Slow Fall 80, Bond of Loyalty
17) Timeless Body, Tongue of the Sun and Moon, Impetuous Endurance
18) Slow Fall 90
19) Empty Body, Fighting Challenge +4
20) Perfect Self, Slow Fall Any, Loyal Beyond Death, Shield Block +3
Seriously, let's say you make it to level 20.
Let's also say you have 14 charisma, 16 strength.
A single level 20 character is expected to be able to take on a CR 16 monster "fairly".
Let's say you charge an adult green dragon, from 180 feet away.
That's +25/+20/+15/+10 punches - (95%/70%/45%/20% to hit) - each attack doing 2d10+3 damage.
The dragon attacks. Let's say something nasty happens and it drops you to the negatives.
That means you get 12 rounds of +23/+23/+18/+13/+8 (85%/85%/60%/35%/10% to hit) attacks.
On average, an adult green dragon has 230 hit points.
On average, you'll do 494.2 damage before you drop for good.
But maybe itr doesn't stand still. Maybe it's trying to run away. You still get to charge it each round.
You'll still average 418.6 damage.
With your fists.
Against a dragon.